Pump



March 12, 1940. I. c. JENNINGS PUMP Filed Sept. 4. 1936 flttorn eys'Patented Mar. 12, 1940 UNITED STATES PATENT OFFICE 26 Claims.

This invention relates to hydroturblne pumps and compressors, and moreparticularly to improvements in the Nash Hytor compressor of the typeshown in the United States patents to Jennings, Nos. 1,718,294, grantedJune 25, 1929, and

1,797,980, granted March 24, 1931.

The compressor or pump shown in these patents comprises an ellipticalcasing in which is arranged a circular rotor having a series of vanesdefining peripheral displacement chambers. Liquid is placed in the pumpcasing, and the rotor is driven at high speed. The liquid in the casingwill travel around with the rotor and by centrifugal action will followthe outline of the 1 casing.

By this arrangement the liquid will be forced into and out of thedisplacement chambers as the rotor turns. Suitable ports are provided sothat the piston action on the liquid thus obtained can be utilizedeither to exhaust or compress a fluid.

In some constructions considerable noise is produced in operation,caused by hydraulic shock in the machine. The water carried around bythe rotor is forced into the displacement chamber of the rotor tocompress the air or other fluid handled by the device, and when eachindividual blade or vane reaches the land of the pumping a chamber, 1.e., the point within the stator closest to the periphery of the rotor,the water or other pumping fluid is cut off with considerable shock,which causes a vibration resulting in noise, and strain on the blades,and necessitates an increase of horse power without doing useful work.Accordingly it is a primary object of the instant invention to minimizethis hydraulic shock and eliminate noise, as well as to increase theefliciency of compressors and pumps of this general reviously it wassupposed that a close clearance was necessary between the rotor and thelands of the stator to prevent leakage of water. It has now beendiscovered, and shown by tests that actually a clearance at these pointsis beneficlal.

Hence, another object of the invention contemplates the deliberateprovision of clearance between the rotor and the narrowest part of thestator or casing.

The provision of this clearance results in largely eliminating thehydraulic shock, as a portion of the pumping liquid is thus permitted.to escape ahead of the rotor. This means that the sharp cut-off ofpumping liquid heretofore thought necessary, is eliminated, therebyreducing hydraulic shock, minimizing vibration and overcoming ancillaryobjections.

At the same time, the increase in the velocity of the pumping liquidinto the next lobe, starts the liquid working in the. next lobe of thecompressor, with attendant increase in efliciency. The volume deliveredby the compressor is slightly reduced by this clearance at the lands,but the required horse power is reduced considerably more, so that notonly is the shock and noise greatly eliminated, but the actualefliciency of the machine is improved.

Other advantages attendant upon the provision of this clearance at thepoints specified, in addition to the elimination of shock and theincrease in operating efllciency are the reduction in liability of thecompressor towards jamming, as it foreign material gets into the pump itis much less likely to jam when the. clearance is provided, and also,the manuiacturer does not have to be held to as close limits asheretofore.

To the attainment of the foregoing and other objects which will appearasthe description proceeds, reference may be made to the accompanyingdrawing, in which:

Figure 1 is a longitudinal sectional elevation of a compressor embodyingthe improvements; and

Figure 2 is a transverse sectional elevation taken along the line 2--2of Figure 1.

Referring more particularly to the drawing in which like referencenumerals designate like parts. there is provided a casing or stator Illhaving a pumping chamber of elliptical shape to provide lobes II and I2separated by lands l3 and I4. Extending through the stator is a shaft l5upon which is mounted the rotor l6, of generally cylindrical shape. Thisrotor, as is usual in Nash pumps, is divided by substantially radialvanes ll into a series of rotor pockets or buckets l8, each of whichforms a displacement chamber having a port or opening 19 in the bottomthereof to establish communication with the inlet ports 20 and Il formedin the stator hub 22. This hub, of course, includes suitable inletpassages 23 and outlet passages 24 communicating with the inlet andoutlet ports. V

A separator member 25 may be provided intermediate the ends of the rotorfor the dual purpose of strengthening the vanes l1 and reducing crosscurrents, or surging within the displacement chambers. The inner wall ofthe pumping chamber may be provided with a similar separating member,opposite the baflie or member 25 as disclosed in Patent No. 1,797,980.

The length of the vanes I1 is such that the diameter of the rotor isless than the shortest internal diameter of the pumping chamber, inorder to provide a'real clearance space indicated at 26 between therotor and the lands l3 and I4. 5 This clearance is of course greaterthan the usual machined running clearance heretofore thought necessaryto' prevent leakage of pumping fluid at the lands.

The amount of clearance provided, that is, the side of the clearancespace between the rotor and the stator at the lands will of course varywith diiferent compressors, but as one example which is illustrative ofthe fact that it is possible to run with a real clearance, it has beenfound that with a rotor of about twelve inches in diameter a clearanceof approximately of an inch at a lobe can be used to advantage. This ofcourse is a real clearance as contrasted with a macbine fit" or runningclearance as now generally used. The foregoing example is intended asbut illustrative and not as limiting. Experience has shown that a rangeof clearance giving beneficial results varies from slightly above toslightly below the given example, i. e., from approximatelythree-fourths percent to two and one-fourth percent, or when, as in thegiven illustrations there are two diametrically opposed lands, thespacing of the rotor from the interior of the stator will range a. totaldistance of from ap- 30 proximately one and one-half percent toapproximately four and one-half percent of the diameter.

As stated heretofore, the amount of clearance varies with differentcompressors; in fact, the

clearance or, for that matter, the total spacing of the rotor will-varywith higher differentials at high speed, which is to be expected becauseof the fact that more of a squeeze will take place. In any event, itwill be obvious that there will 40 be a proportioned relation betweenthe amount of clearance, or the total spacing of the rotor on a diametertaken through the lands, and the rotor diameter. The ranges referred toherein, when given in terms of total distance will, as

stated above, vary from approximately one and one-half to four andone-half percent, or when given in terms of clearance, i. e., between aland and the rotor periphery, will be just half, or from three-fourthsto two and one-fourth percent of the rotor diameter.

The separating member 25 and the shrouds 21 may be extended beyond thevanes l'l if desired, to maintain a running fit with the stator, butthis will in no wise affect the clearance between the outer edges of thevanes l1 and the interior of the casing.

In the operation of pumps provided with a clearance as above describedit has been found that hydraulic shock, vibration, noise, and bladestrain have been largely eliminated, and that while there will be somereduction in volume there is a greater reduction in horse powerrequired, which means a net gain in efliciency, and

further the liability of jamming when foreign material gets intothe'pump is greatly reduced. Obviously, manufacturing costs are reducedin that the manufacturer does not have to be held to as close limits asheretofore.

While the liquid used in the pumping action 7 is designated water in thespecification, it will be understood that this designation isillustrative only, as'other liquids may be substituted without impairingthe utility or advantages of the invention or necessitating anymechanical altera- 75 tion therein.

Having thus fully described my invention, what I claim as new and desireto secure by Letters Patent is: 4

1. In a hydro-turbine pump of the type using liquid as apumping medium,the combination of 5 a substantially circular rotor with an ellipticalcasing providing lobes therefor, said rotor having vanes providingdisplacement chambers about the periphery of the rotor, the periphery ofthe vaned portion of the rotor being spaced on a 1. diameter through thelands of said casing a total distance approximating from one andone-half 'percent to four and one-half percent of the rotor diameter,whereby to pass pumping liquid freely from one lobe to the next adjacentlobe, thereby II to increase the velocity of the pumping liquid in saidadjacent lobe and reduce hydraulic shock.

2. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a substantially circular rotor with an ellipticalcasmg providing lobes therefor, said rotor having vanes providingdisplacement chambers about the periphery of the rotor, the periphery ofthe vaned portion of the rotor being spaced-from the lands to provideclearancesbetween the rotor and the lands approximating fromthree-fourths percent to two and one-fourth percent of the rotordiameter, whereby to insure escape and free passage of thepumping liquidahead of the vaned portion of the rotor from one lobe to the next, toreduce hydraulic shock and increase operating efliciency.

3. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a substantially circular rotor provided withperipheral displacement chambers, with a pump casing therefor havingpumping lobes and a land, the greatest diameter of said rotor throughsaid chambers being less than the cross sectional diameter of saidcasing through said land, to provide clearances between the periphery ofthe 40 vaned portion of said rotor and the land approximating fromthree-fourths percent to two and one-fourth percent of the rotordiameter, whereby pumping liquid will pass freely from one lobe to thenext adjacent lobe to increase the 45 velocity of the liquid in saidadjacent lobe and reduce hydraulic shock.

4. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a. substantially circular rotor provided with pe- 5oripheral displacement chambers, with a pump casing therefor having aplurality of pumping lobes separated by lands, the greatest diameter ofsaid rotor through said chambers being less than the cross sectionaldiameter of the casing 55 through said lands, the periphery of the vanedportion of said rotor being spaced on a diameter through the lands ofsaid casing a total distance approximating from one and one-half percentto four and one-half percent of the rotor diameter. 5

5. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a substantially circular rotor provided withperipheral displacement chambers, with a pump casing therefor having aplurality of successively 5 operative pumping lobes separated by lands,and means to start the pumping liquid to work in one lobe prior tocompletion of its work in the preceding lobe, including clearancesbetween the rotor and the lands approximating from threefourths percentto two and one-fourth percent of the rotor diameter.

6. In a hydro-turbine pumpof the type using liquid as a pumping medium,the combination of a substantially circular rotor providedwithperipheral displacement cahmbers, with a pump casing therefor having aplurality of successively operative pu'mping lobes separated by lands,and

means to eliminate hydraulic shock including a spaced relation oftheperiphery of the rotor through said displacement chambers to thelands on a diameter through the lands, a total distance greater thanrequired for free running clearance,

wherein said total distance approximates from liquid as a pumpingmedium, the combination of a substantially circular rotor provided withperipheral displacement chambers, with a pump casing therefor having aplurality of successively operative pumping lobes separated by lands,and means for starting the pumping liquid to work in one lobe prior tocompletion of its work in the preceding lobe, including a spacedrelation of the periphery of the rotor through said displacementchambers to the lands on a diameter through the lands, a total distancegreater than required for the free running clearance, said totaldistance approximating from one and one-half percent to four andone-half percent of the rotor diameter.

8. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a substantially circularrotor provided withperipheral displacement chambers, with a pump casing therefor having aplurality of successively operative pumping lobes separated by lands,said rotor being spaced about its periphery through said displacementchambers from said lands of the casing on a diameter through the lands,a total distance approximating from one and onehalf percent to four andone-half percent of the rotor diameter, whereby to release a portion ofthe pumping liquid in one lobe and to start said released portion ofliquid to work in a successive lobe, prior to completion of the pumpingaction in the first lobe, thus minimizing hydraulic shock at the lands.

9. In a hydro-turbine pump of the type using liquid as a pumping medium,the combination with a rotor provided with peripheral displacemeritchambers, and a pump casing therefor, having a plurality of successivelyoperative pumping lobes separated by lands, of means to increase thevelocity of pumping liquid from one lobe into a successive lobe and toreduce hydraulic shock and minimize vibration including a proportionedrelation of the rotor diameters with respect to the intenal diameter ofthe casing through said displacement chambers from land to land such asto space the periphery of the rotor from said lands ona diameter throughthe lands, a total distance approximating from one and one-half percentto four and one-half percent of the rotor diameter to provideclearances, effective to release a portion of the pumping liquid in onelobe and to start said released portion of liquid to work in asuccessive lobe prior to completion of the pumping action in the firstlobe.

10. In a hydro-turbine pump of the type using liquid as a pumpingmedium, the combination of a rotor and a stator providing a lobe casingtherefor, the greatest diameter of the operating portion of said rotorbeing appreciably less than the smallest internal diameter of saidcasing, and the periphery of said operating portion being spaced at eachof the lands of said casing a distance approximating from three-fourthspercent to two and one-fourth percent of the rotor diameter, whereby topass pumping liquid freely from one lobe into the next adjacent lobe,during the pumping action, thereby to increase the velocity of thepumping liquid in said adjacent lobe, and reduce hydraulic shock.

11. In a hydro-turbine pump of the type using liquid as a pumpingmedium, the combination of a rotor and a stator providing a lobe casingtherefor, and means providing a clearance between the operating portionof said. rotor and eating at the smallest internal diameter of saidcasing, sufficiently great to pass pumping liquid freely from one lobeinto the next adjacent lobe, during the pumping action, thereby toincrease the velocity of the pumping liquid in said adjacent lobe, andreduce hydraulic shock, said clearance approximating from three-fourthspercent to two and one-fourth percent of the rotor diameter.

12. In a hydro-turbine pump of the type using liquid as a pumpingmedium, the combination of a rotor and a stator providing a lobe casingtherefor, the greatest diameter of the operating portion of said rotorbeing appreciably less than the smallest internal diameter of saidcasing, and the periphery of said operating portion being spaced at eachof the lands of said casing a distance approximating from three-fourthspercent to two and one-fourth percent of the rotor diameter, whereby topass pumping liquid freely from one lobe into the next adjacent lobe,during the pumping action, thereby to increase the velocity of thepumping liquid in said adjacent lobe, and reduce hydraulic shock, andmeans at the periphery of the rotor effective to maintain a closerunning fit between the rotor and stator.

13 In a hydro-turbine pump of the type using liquid as a pumping medium,the combination of a rotor and a stator providing a lobe casingtherefor, and means providing a clearance between the operating portionof said rotor and casing at the smallest internal diameter of saidcasing, sufiicietly great to pass pumping liquid freely from one lobeinto the next adjacent lobe, during the pumping action, thereby toincrease the velocity of the pumping liquid in said adjacent lobe, andreduce hydraulic shock, said clearance approximating from three-fourthspercent to two and one-fourth percent of the rotor diameter, and meansat the periphery of the rotor effective to maintain a close running fitbetween the rotor and stator.

14. In a hydro-turbine pump of the type using liquid as a pumpingmedium, the combination of a substantially circular rotor with anelliptical casing providing lobes therefor, said rotor having vanesproviding displacement chambers about the periphery of the rotor, saidrotor also having shrouds defining side walls for said chambers, thegreatest cross sectional diameter of said rotor through said vanes beingappreciably less than the smallest internal diameter of said casing, theperiphery of the vaned portion of said rotor being spaced at the landsof said casing a distance effective to pass pumping liquid freely fromone lobe into the next adjacent lobe, during the pumping action, therebyto increase the velocity of the pumping liquid in said adjacent lobe,and reduce hydraulic shock, and the cross sectional diameter of saidrotor through said shrouds being greater than the diameter through thevanes.

15. In a hydro-turbine pump of the type using liquid as a pumpingmedium, he combination of a substantially circular rotor provided withperipheral displacement chambers, said rotor also having shroudsdefining side walls for said chambers, with a pump casing thereforhaving a pumping lobe and a land, the greatest diameter of said rotorthrough said chambers being less than the cross sectional diameter ofsaid casing through said land, and the periphery of the 8 chamberedportion of said rotor being spaced from said land a distance eifectiveto pass pumping liquid freely from one lobe into the next adjacent lobe,during the pumping action. thereby to increase the velocity of thepumping liquid in 10 said adjacent lobe, and reduce hydraulic shock,

and the cross sectional diameter of said rotor through said shroudsbeing greater than the diameter through the vanes.

16. In a hydro-turbine pump of the type using 16- liquid as a pumpingmedium, the combination of a substantially circular rotor provided withperipheral displacement chambers, saidrotor' also having shroudsdefining side walls for said chambers, with a pump casing thereforhaving a plu- 0 rality of successively operative pumping lobes separatedby lands, and means to start the pumping liquid to work in one lobeprior to completion of its work in the preceding lobe, including aclearance between the operative portion of the rotor and the landseffective to pass the pumping liquid freely from lobe to lobe duringpumping action, thereby increasing the velocity of the pumping liquid asit enters a lobe, and the cross sectional diameter of said rotor throughsaid shrouds being greater than the diameter through the vanes.

17. In a hydro-turbine pump of the type using liquid as a pumpingmedium, the combination of a substantially circular rotor provided withperipheral displacement chambers, said rotor also having shroudsdefining side walls for said chambers, with a pump casing thereforhaving a plurality of successively operative pumping lobes separated bylands, and means to reduce hydraulic shock including a spaced relationof the periphery of the rotor through said displacement chambers to thelands a distance greater than required for free running clearance,whereby pumping liquid passes freely ahead of the displacement chambers,from one lobe into the next adjacent lobe, during the pumping action,and

the cross sectional diameter of said rotor through said shrouds beinggreater than the diameter through the vanes.

18. In a hydro-turbine pump using liquid asthe pumping medium thecombination of a rotor having a portion operating in the pumping medium,with a lobe casing therefor, having lobes separated by lands, and means,including the operating portion of said rotor, to pass pumping liquidfreely from one lobe into the next adjacent lobe during the pumpingaction, to increase the velocity of the pumping liquid in said adjacentlobeand to reduce hydraulic shock, said rotor being spaced from each ofthe lands a distance approximating from three-fourths percent to two andone-fourth percent of the rotor diameter.

19. In a hydro-turbine pump using liquid as the pumping medium, thecombination of a rotor having a portion operating in the pumping medium,with a lobe casing therefor, having lobes separated by lands, and meansincluding the operating portion of said rotor to increase the 7 velocityof the pumping liquid above normal from one lobe to the next adjacentlobe, during pumping action, to start the liquid working in saidadjacent lobe and to reduce hydraulic shock, said rotor being spacedfrom each of the lands a disu tanoe approximating from three-fourthspercent to two and one-fourth percent of the rotor diameter.

20. .In a hydro-turbine pump using liquid as the pumping medium, thecombination of a rotor having a portion operating in the pumping 5 1 andthe casing.

21. In a hydro-turbine pump using liquid as the pumping medium, thecombination of a rotor having a portion operating in the pumping medium,with a lobe casing therefor, said rotor having vanes providingdisplacement chambers about the periphery of the rotor, and shroudsdefining side walls for said chambers, the diameter of the rotor throughsaid vanes being less 95 than the diameter of the rotor through saidshrouds, and means providing a close running fit between said shroudsand the interior of the casing.

22. In a hydro turbine pump using liquid as a 30 pumping medium, thecombination of a pumping chamber having a lobe and a land, with a rotorhaving a portion operating in the pumping medium, said rotor havingvanes providing displacement chambers about the periphery of the rotor,and shrouds defining side walls for said chamber, and means providing aclearance between the periphery of the rotor at the vanes and theinterior of the pumping chamber at said land, approximating from one andone-half per- 40 cent to four and one-half percent the diameter of therotor.

23. In a hydro turbine pump using liquid as a pumping medium, thecombination of a pumping chamber having a lobe and a land, wtih a rotor45 having a portion operating in the pumping medium, said rotor havingvanes providing displacement chambers about the periphery of the rotor,and shrouds defining sidewalls for said chamber, means providing aclearance between 50 the periphery of the rotor at the vanes and theinterior of the pumping chamber at said land approximating from one andone-half percent to four and one-half percent the diameter of the rotor,and means providing a close running fit 55 between the rotor and theinterior of the chamber adjacent the periphery of the shrouds.

24. In a hydro turbine pump using liquid as a pumping medium-thecombination of a pumping chamber having a lobe and a land, with a rotor0 having a portion operating in the pumping medium, said rotor havingvanes providing displacement chambers about the periphery of the rotor,means providing a clearance between the periphery of the rotor at thevanes and the in- 65 terior of the pumping chamber at said landapproximating from one and one-half percent to four and one-half percentthe diameter of the rotor, and means providing a close running fitbetween the peripheral edges of the rotor and the interior of thechamber, adjacent the land.

25. In a hydro turbine pump using liquid as a pumping medium, thecombination of a pump casing for said pumping medium and provided with alobe and a land, of a rotor having a portion operating in the pumpingmedium, said rotor having vanes providing displacement chambers aboutthe periphery of the rotor, and shrouds defining side walls for saidchambers, the cross sectional diameter of the rotor through the vanesbeing appreciably less than the cross sectional diameter of the casingthrough that portion of the land adjacent the vanes, and the crosssectional diameter of the casing at points adjacent the land and theshrouds being substantially that of the cross sectional diameter throughthe rotor at the shrouds, said rotor and casing being proportioned tomaintain a close running fit between said shrouds and the casing.

26. In a hydro turbine pump using liquid as a pumping medium, thecombination of a pump casing forsaid pumping medium and provided with alobe and a land, of a rotor having a portion operating in the pumpingmedium, said rotor having vanes providing displacement chambers aboutthe periphery of the rotor, and shrouds defining side walls for saidchambers, means providing a clearance between the vanes and that portionof the land which co-operates therewith greater than the clearancebetween the shrouds and that portion of the land which co-operates withthe shrouds, and means providing a close running fit between the shroudsand its co-opcrating portion of the land.

IRVING C. JENNINGS.

